This specialization of std::ctype encapsulates character classification features for type char. Unlike general-purpose std::ctype, which uses virtual functions, this specialization uses table lookup to classify characters (which is generally faster).

The base class std::ctype<char> implements character classification equivalent to the minimal "C" locale. The classification rules can be extended or modified if constructed with a non-default classification table argument, if constructed as std::ctype_byname<char> or as a user-defined derived facet. All std::istream formatted input functions are required to use std::ctype<char> for character classing during input parsing.